Not OP, but I think it would best fit in the websites setting view. I don’t think it should go in the brush menu as it impacts all websites. Since appearance settings are for the appearance of the browser, it also would not make sense to go there (though this would be more intuitive). Therefore, I would advocate for placing it in website settings. There’s already a system in place there for defaults for websites, and overrides, so little extra effort would be needed for implementation. The brush menu theme setting would then be used to set website overrides. How does this sound?